Current prevention efforts to curtail HIV/STD risk among adolescents has shown some efficacy, but interventions that are both more effective and more easily diffused still need to be developed and carefully evaluated. At the same time, prior research on media and classroom preventive interventions has shown that interventions designed to be more novel and participatory are more effective in altering a number of crucial adolescent health risk behaviors. Research examining the effectiveness of tailored web-based programs on adolescent health behaviors have demonstrated that behaviors were successfully changed by including elements designed specifically to attract, hold the attention of, and persuade those most likely at risk. These highly interactive, vivid, quickly-paced stimuli may be effective in eliciting the attention of the population-of- interest for this research project: those most likely to take risks that increase the likelihood of HIV/STD exposure. Our objectives are to 1) adapt the successful sexual risk behavior prevention curricula to a self- administered Web-based curriculum that will target high sensation-seeking and low sensation-seeking youth with separate messages;2) implement the model program in the early high school environment;and 3) evaluate the effect of the intervention on the change in adolescents'intentions to remain abstinent from sexual intercourse, to avoid the use of drugs before sex and to use condoms for vaginal or anal intercourse. Other evaluations include knowledge, salience of HIV/STD, perceived risk of contracting HIV/STD, and self-efficacy skills related to remaining abstinent, negotiating safe sexual behavior, and using condoms. The website intervention will promote abstinence among youth who have not yet started having sex and promote condom use and other safe-sex practices among those who are engaging in sex and intend to continue for the goal of prevention/reduction of HIV/STD transmission among youth. A two-phase project is proposed to address these aims. The first phase (Years 1-2), will involve intervention development through focus and reaction groups that help refine issues and design effective curricular materials and multimedia production and programming in the Internet environment. Using a software engine developed in previous Internet-based prevention research, the HIV/STD prevention program will tailor messages intended to prolong sexual abstinence for students who are not yet sexually active and messages to increase condom use, and reduce other risky sexual behaviors for those who are sexually active. The Internet- based program will be implemented and evaluated in the second phase of the project (Years 3-5) using a group-randomized pretest-posttest control group design, with public schools in Albuquerque and Denver as the unit of analysis. The impact of the intervention on HIV/STD prevention skills, behavioral intentions, and sexual risk-taking behaviors will be assessed in three follow-up posttests (at completion of the intervention, 6-month post, and at 1-year post). The final year of the study will involve final data analysis and field trial outcomes. PUBLIC HEALTH RELEVANCE: The rate of HIV and STD infection as well as related negative consequences of early onset of sexual behavior among adolescents, especially minority adolescents, continues to be a concern for prevention researchers. Alcohol use is also clearly a correlate of early initiation of sexual activity and may be related in complex ways to sexual risk-taking. By combining research programs and expertise in crafting preventive media messages for high sensation seekers, employing information exposure and sensation seeking principles, and utilizing our expertise in developing and testing multimedia prevention websites, we will develop a HIV/STD and alcohol prevention website for adolescents that will be tailored to the adolescent user's level of sensation seeking. As a result, the website intervention to be developed will be grounded in empirically verified prevention principles, and will have the potential to be quickly and widely disseminated once the efficacy of the website has been determined.